Identification of genes differentially expressed in husk tomato (Physalis philadelphica) in response to whitefly (Trialeurodes vaporariorum) infestation

Abstract

Plants respond to phloem-feeding whiteflies by extensive changes in gene expression. To identify differentially expressed genes in husk tomato plants (Physalis philadelphica) infested with Trialeurodes vaporariorum, young plants were challenged with adult whiteflies, and forward and reverse subtractive libraries were constructed from infested leaves at 5 and 15 days after infestation. Several genes were identified as up-regulated; these included a diversity of genes involved in plant defense responses, protein synthesis or degradation, and cell wall fortification or modification. Genes required for amino acid biosynthesis, lipid metabolism and synthesis, including cell surface components such as suberin, responses to stress, photosynthesis and other functions, were similarly induced. Down-regulated genes were also identified, most prominently kinases and aquaporin genes. Similarities in defense responses between tomato and P. philadelphica were noted regarding the expression of certain genes in response to nematode, aphid, or whitefly. A role for abscisic acid, brassinosteroids, and cytokinins in the regulated response to whitefly infestation in P. philadelphica was also implied by the expression pattern of phytohormone-associated genes, including genes coding for proteins containing F-box motifs. Differential expression of selected genes was validated by quantitative real-time PCR. The possible role played by some of these genes during whitefly infestation is discussed.